Mystery of Bizarre Icelandic Lava Pillars Solved

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The mystery of a series of strange, knobby pillars of rock that
formed in Iceland has been solved.

A creeping lava flow and a stream of water mixed to create
hollow, rough pillars that dot the Skaelinger Valley in
Iceland. The surprise is that these towers could form at all
on land. Until now, researchers thought that whenever water and
lava met on land, either explosive steam or pillow-shaped lava
formed.

"These had never been observed or described before as features
seen on land. They've been described at mid-ocean ridges 2 miles
[3 km] under water," said study co-author Tracy Gregg, a
geologist at the University at Buffalo in New York.

Troll wars?

Gregg was hiking in Iceland in 1998 when she came upon the
strange pillars, which almost look like trees without branches.
Some of the tallest are 8 feet (2.4 meters) high, and up to 3.3
feet (1 m) wide.

"I was so excited. As soon as I saw these things I knew what they
were," Gregg told LiveScience.

At mid-ocean ridges, or points in the deep ocean where the
continental plates are peeling apart, lava seeps out of the ocean
floor. Hot water rises up through this
pillow lava and cools the nearby lava into rock, and as lava
levels rise, spires grow, and remain even after lava flows have
ebbed. [ 50
Amazing Volcano Facts ]

But no one had ever documented such pillars on land.

Unfortunately, Gregg didn't get a chance to study the pillars
again until 2010, when her graduate student Kenneth Christie
received a grant to study the structures in Iceland.

Pillar formation

Gregg and Christie concluded that Skaelinger's odd formations
formed just like underwater lava pillars, during the famed Laki
Eruption of 1783, when a volcanic fissure in southern Iceland
oozed lava for eight months. That eruption was so big that it
killed at least 50 percent of the island's livestock and a
quarter of its population. Benjamin Franklin noted Europe's hazy
skies from the volcano's ash in his journal at the time, and made
some of the first speculations to link volcanoes
and climate, Gregg said.

As slow-moving lava inched its way across the Skaelinger Valley,
the lava created a temporary dam on the river that flows through
the valley, probably forming a small pond, Gregg said. The
meeting of slow-moving lava and water formed spires similar to
those found deep in the ocean.

Once lava levels in the valley fell, the hardened, hollow pillars
remained.

The findings may force geologists to rethink how lava and water
interact on land. Normally, when water and lava meet, water
either drowns the lava, forming pillowlike structures, or the
lava heats the water in a flash till it turns to steam that
explodes, Gregg said.

Iceland and Mars

It's also possible that lava pillars may occur elsewhere on
Earth. These spires, born in past eruptions, can also provide
insight into the historical climate, Gregg said.

"If we find them somewhere else on Earth, it tells us that when
that lava was in place, that the area was wet," she said.